GCN Circular 44805
Subject
GRB 260603A: EP-FXT follow-up observation
Event
Date
2026-06-03T14:21:26Z (a day ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Z. X. Li, G. L. Huang, J. Y. Cao (IHEP, CAS), J. W. Hu, Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team:
EP-FXT performed an automatic follow-up observation of GRB 260603A detected by SVOM/ECLAIRs (SVOM/sb26051504, ZHAO et al., GCN 44787). The follow-up observation started at 2026-06-03T07:38:06 UTC, approximately 2 hours after the SVOM trigger, with a total exposure time of 2.4 ks.
On-ground analysis of the FXT data found an uncatalogued source within the ECLAIRs error circle at R.A., Dec. = 233.1435, 40.0258 deg (J2000) with an uncertainty of about 10 arcsec (radius, 90% C.L. statistical and systematic). This position is consistent with the optical counterpart (Guelfand et al., GCN 44791). The average FXT 0.5-10 keV spectrum can be fitted with an absorbed power-law model, with the hydrogen column density of 1.7 (-0.8/+0.8) × 10^21 cm^-2 and a photon index of 2.4 (-0.3/+0.3). The derived average unabsorbed flux in the 0.5-10 keV band is 4.0 (-0.4, +0.5) x 10^(-12) erg/s/cm^2.
Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).